It is generally known for a silver-containing catalyst to be employed in the preparation of ethylene oxide from ethylene. See for example U.S. Pat. No. 3,962,136 and also the literature cited therein. In order to obtain improved silver catalysts, efforts have been directed for many years towards modifying the silver catalysts with the aid of promoters. For example, the above-mentioned U.S. Pat. No. 3,962,136 describes a process in which a silver compound is applied to a carrier, after which the applied silver compound is reduced to silver and in which additionally a promoter in the form of potassium oxide, rubidium oxide or cesium oxide or a mixture thereof is present on the carrier.
In co-pending U.S. application Ser. No. 874,913, filed June 16, 1986, now abandoned, is described a process for the preparation of a silver-containing catalyst suitable for the oxidation of ethylene to ethylene oxide, whereby a silver compound and, if desired, a promoter are applied to an alkali enriched carrier, after which the silver compound is reduced to metallic silver, and in which process the alkali enriched carrier has been prepared by mixing an aluminum compound with a salt of an alkali metal and by calcining the mixture. The obtained silver catalyst has a good stability.
I has now been found that silver catalysts may be prepared with even better stability by using the process of the instant invention.